Plural-stage axial compressor



A ril 28, 1970 R. STRUB PLURAL-STAGE AXIAL COMPRESSOR 2 Sheets-Sheet 1 Euled June 26, 1968 Inventor:

Rene Strub ATTORNEYS April 28, 1970 R STRUB PLURAL-STAGE AXIAL COMPRESSOR 2 Sheets5heet 2 Filed June 26, 1968 Inventor: Rene Strub BYgw w M-JIJZLV awflieflwh ATTORNEYS United States Patent 3,508,839 PLURAL-STAGE AXIAL COMPRESSOR Rene Strub, Winterthur, Switzerland, assignor to Sulzer Brothers Limited, Winterthur, Switzerland, a Swiss company Filed June 26, 1968, Ser. No. 740,271 Claims priority, application Switzerland, Jan. 15, 1968, 568/68 Int. Cl. F01d 9/02; F04d 27/00 U.S. Cl. 415-149 2 Claims ABSTRACT THE DISCLOSURE A plural-stage axial compressor having variable pitch stator blades, in which a blade pitch-adjusting sleeve includes a plurality of sections each engaging the pitchadjusting levers of the blades of one or more stator blade stages, and also including a spacing ring disposed between and fastened to each pair of axially adjacent sleeve sections.

The present invention pertains to a plural-stage axial compressor whose stator blades are rotatably mounted in an annular stator blade carrier for adjustment of the angular position of those blades with respect to the gas being compressed in its passage between the rotor blades of successive stages. These stator blades are provided with adjusting levers so that they can be'adjusted together by means of an axially movable sleeve which engages the levers, in accordance with the power level at which the compressor is to be driven for a given operating program. In plural-stage axial compressors having variable pitch stator blades, the length of the levers and the angular orientation thereof with respect to their blades is desired to be chosen so that under all conditions of operation within a given operating program, the compressor will operate at optimum conditions. However such an operating program does not always remain unchanged over long periods of time. Thus changes may be made therein because of modifications in the installations, such as blast furnaces or burners, served by the compressor. Indeed a change of program may have been anticipated at the outset. Notwithstanding the adjustability of the stator blades, the compressor can then not be employed according to the new program with optimum effect.

In accordance with the invention, the adjusting sleeve is made up of at least two annular setcions, parted between the levers of the stator blades of two successive stages of the compressor. These sections are provided with flanges and there is inserted between them and fastened thereto a ring of such axial length that the blades can be set to the position which is optimum for the operating program applied to the compressor. By employing between each pair of adjacent sleeve sections a spacing ring of suitable axial length, the relative angular positions of the stator blades controlled by those two sections can be varied in accordance with operational requirements.

By means of the invention therefore it is possible to adapt the compressor, in a short time and with small expenditure in effort and equipment, to changes in its initial operating program so that it will again operate optimally.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be further described in terms of an exemplary embodiment by reference to the accompanying drawings in which:

FIG. 1 is an axial section of a compressor according to the invention; and

FIG. 2 is a cross-section of the compressor of FIG. 1.

In the drawings the rotor 1 of the compressor is provided with a plurality of circular arrays or sets 3 of rotor blades belonging to successive compressor stages. A circular set 4 of stator blades is disposed between each two adjacent sets of rotor blades. The stator blades are supported at shafts 6 in an annular stator blade carrier 5 for rotation about those shafts. Exteriorly of the housing or carrier 5 an adjusting lever 7 is afiixed to the shaft of each stator blade, each of these levers ending in a peg 8. The pegs 8 for each stage are engaged, via individual slides not shown, in the groove of a grooved ring 9 which is aflixed to the adjusting sleeve generally indicated at 10 so that upon axial shift of the sleeve 10 the blades 4 will be rotated about their shafts 6 to change the pitch thereof. Thus they can during operation of the compressor be adjusted to the output desired for the compressor according to the operating program thereof. The adjusting sleeve 10 is provided with keys 11, of which one is shown in FIG. 2, moving in axially extending keyways 12 of an exterior housing 20 so that the sleeve can be moved or reciprocated axially by means of a control member not shown.

The sleeve 10 is divided at the locations of the spacing rings 13 and 14 into three annular sections 15, 16 and '17, each of which serves in the embodiment illustrated to adjust the angular position of the stator blades of a plurality of stages. Each of these sections or parts is provided with a flange or flanges 18 at those of the spacing rings 13 and 14 axially bounding those parts respectively, and the flanges and rings are held together by means of bolts 19. By means of the spacing rings 13 and 14, the individual parts 15, 16 and 17 of the adjusting sleeve can be held at suitable axial spacing from each other so that the stator blades of the various stages can be angularly set substantially to optimum position for the current operating program. It may suffice it only two groups of blades are so adjusted, i.e. it may sutfice if the sleeve 10 is divided into two instead of three parts. A further approach to optimum values is obtained if the stator blading is divided into more than two groups, each including a reduced number of stages. The best result is obtained by providing a spacing ring 13 between each pair of adjacent grooved rings 9 of the adjusting sleeve, so that there is provided a sleeve part or section for the stator blades of each stage of the compressor, and so that the axial spacing of each such section from its adjacent sections can be adjusted by the interposition of spacing rings of various axial lengths.

It is not unusual to provide plural-stage axial compressors for installations which subsequently are operated according to a program different from the initial one, for example in the event of an increase in size of the plant or in the event of an increase in output or of operating pressure. In such cases suitable adjustment can often be made by changing the angular position of the blades with respect to the direction from which the gas to be compressed approaches. Thus it is possible for a compressor, which as initially programmed operates under a given partial load for most of the time, to be thereafter required to be operated according to a new program. The adjustment of the stator blades will always be chosen to achieve the highest degree of efficiency in that range of loads which is most often encountered in the current operating program. By changing the spacing rings 13 and 14, the necessary matching to the operating values of the current program can be achieved with minimum cost and in minimum time.

While the invention has been described hereinabove in terms of a presently preferred embodiment thereof, the invention itself is not limited thereto but rather comprehends all modifications of and departures from that embodiment.

I claim: References Cited 1. A plural-stage axlal compressor comprising a rotor, UNITED STATES PATENTS a stator-blade carrier, a plurahty of annular arrays of stator blades rotatably supported in the blade-carrier, a 2,778,564 1/1957 Hall-lord et pitch-adjusting lever coupled to each of said blades, a 5 3,303,989 2/1967 Rlmk at plurality of blade pitch-adjusting sleeve sections each en- 3,342,406 9/1967 Baumann et gaging the levers of the blades of at least one of said ar- FOREIGN PATENTS rays, and a replaceable spacing ring disposed between and fastened to each pair of axially adjacent Ones of said 1238098 6/1960 Franck sleeve sections. 10 LEONARD H. GERIN, Primary Examiner 2. A compressor according to claim 1 wherein said sleeve sections include flanges adjacent each of said rings to which said sections are respectively fastened. 415.160 

